ALU 301 Chapter 4|Complete Questions with 100% Correct Answers

ALU 301 Chapter 4|Complete Questions with 100% Correct Answers The Humoral System Predominant theory of disesase in Western culture for over 200 years. It taught that the body is composed of four balanced humors, or fluids: blood, phlegm, black bile, and yellow bile - which are found in the heart, brain, spleen and liver. (Hippocrates created this.) Germ Theory of Disease Developed late in the 19th century by Louis Pateur and Robert Koch. This theory postulated that each disease is caused by a microbe specific for that disease. Koch's Postulates Used to determine if disease is attributable to a certain microorganism: 1. The same pathogen must be found in all diseased individuals w/ same sxs. 2. The pathogen must be isolated from the individual w/ the disease and grown in a culture. 3. The same disease must be induced in an experimental animal by transfer of the cultured pathogen. 4. After the disease develops, the same pathogen must be isolated fromt he experimental animal. When were viruses first seen? 1931 with the invention of the electron microscope. When was the first vaccine? 1796 - used to prevent smallpox. Dr. Joseph Lister Pioneered the use of carbolic acid in 1865 as an antiseptic both on his hands and as a dressing for wounds to prevent infection. First effective antibiotic drug? Sulfonamide, 1935 Reservoir The native habitat in which an infective agent lives and multiplies. Four types: 1) symptomatic individuals, 2) carriers, 3) animals, 4) water, food, soil, air, fomites (inanimate objects that carry disease-causing microbes). Infection Occurs when there is an entry and multiplication of a microorganism or parasite in the body of a host. Vector Usually an insect that injects the microbe through a bite, but it can refer to a creature that transports the infective organism to the host. Infectious Disease process Microbes must invade, infect and disrupt the cells of the host for disease to occur. Direct detection methods Use the microscope to view the microbe obtained in a tissue, body fluid or excreta sample. Gram Stain method Used to differentiate between bacteria that have relatively thick cell walls and take up the stain readily (gram-positive) and those that have thinner cell walls surrounded by an outer membrane that does not stain (gram-negative). Gram-positive bacteria Streptococci and staphylococci Gram-negative bacteria Pseudomonas and E. coli Acid-fast stain Used to identify organisms that retain the staining dye even after being washed in an acid solvent, i.e. acid-fast bacteria (i.e. mycobacterium species that cause tuberculosis and leprosy). Agar Gelatin-like medium used to culture bacteria since bacteria do not use it for food. Culturing viruses Requires using a medium of living cells since viruses cannot replicate in vitro. Why culture bacteria or virus? To identify what they are; to test the efficacy of specific antibiotics. Immunodiagnosis Testing for the presence in serum of antibodies produced by the immune system in reaction to an infection. Test for Hep A, B & C and Helicobacter pylori use this technique. Nucleic Acid Probe Diagnostic technique based on the fact that every species of microbe-bacteria, virus, fungi or parasite-has some unique sequence of genes in either its DNA or RNA that differentiate it from all other microbes. Can also be used to monitor the response to therapy in some diseases, such as Hep C and HIV, where these tests can monitor viral load or the number of viral copies/ml. Amplification techniques Employed to produce enough of the specific DNA gene sequence for identification. Ex: Polymerase chain reaction (PCR) - amplifies a single DNA molecule into many billions of molecules. Infectious disease causing organisms Bacteria, viruses, fungi, and parasites Bacteria Living cell organisms that exist almost everywhere on the planet. 10,000 species are recognized. Bacteria classification system Cocci are spherical; bacilli are rod-shaped; spirochetes are spiral; vibrios are comma-shaped. Bacteria groupings Diplo - means paired; strepto - means arranged in chains; staphylo - means arranged in clusters. Anaerobic bacteria Cannot survive in the presence of oxygen. Aerobic bacteria Must have oxygen to survive. Antibiotics Substances produced by microorganisms that kill other microorganisms; natural byproducts of cellular metabolism. Age of antibiotics began in 1929 - Alexander Fleming discovered penecillium. Penicillin Isolated and produced in the 1940s; very effective against Gram positive staphylococci and streptococci - two types of bacteria that cause a large percentage of human infections. Viruses Considered non-living since they don't have a cellular structure; have a protein coat surrounding a nucleic acid; they require the metabolic machinery of the cell they infect to reproduce; can contain DNA or RNA, but never both. Envelope viruses Have an envelope of lipids, proteins, and carbohydrates around their protein coat. *If a virus doesn't have an envelope, it is referred to as naked. Fungi Includes both yeast and molds; aerobic and require organic nutrients to live. 100,000 species of fungi - only about 100 are infectious to humans and most are saprophytes (fungi that live on decaying organic matter). Systemic fungal infections Quite difficult to treat, requiring therapy for weeks to months in many cases. Parasites Organisms that cause disease in humans, but are not bacteria, viruses or fungi. They need to invade a human body to complete their life cycle. Many parasitic diseases occur in the tropics.